docs(vertex-ai-gemini): Add Gemini PDF support docs and add IT

- Add test case for PDF document summarization using Gemini multimodal capabilities
- Update documentation to reflect PDF support in model comparison table
- Add PDF format to multimodal capabilities documentation

models/spring-ai-vertex-ai-gemini/src/test/java/org/springframework/ai/vertexai/gemini/VertexAiGeminiChatModelIT.java

@@ -49,6 +49,7 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.core.convert.support.DefaultConversionService;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.Resource;
+import org.springframework.util.MimeType;
 import org.springframework.util.MimeTypeUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -246,6 +247,22 @@ class VertexAiGeminiChatModelIT {
 		// https://github.com/GoogleCloudPlatform/generative-ai/blob/main/gemini/use-cases/intro_multimodal_use_cases.ipynb
 	}
 
+	@Test
+	void multiModalityPdfTest() throws IOException {
+
+		var pdfData = new ClassPathResource("/spring-ai-reference-overview.pdf");
+
+		var userMessage = new UserMessage(
+				"You are a very professional document summarization specialist. Please summarize the given document.",
+				List.of(new Media(new MimeType("application", "pdf"), pdfData)));
+
+		var response = this.chatModel.call(new Prompt(List.of(userMessage)));
+
+		System.out.println(response.getResult().getOutput().getContent());
+
+		assertThat(response.getResult().getOutput().getContent()).containsAnyOf("Spring AI", "portable API");
+	}
+
 	record ActorsFilmsRecord(String actor, List<String> movies) {
 
 	}

spring-ai-docs/src/main/antora/modules/ROOT/pages/api/chat/comparison.adoc

@@ -21,7 +21,7 @@ This table compares various Chat Models supported by Spring AI, detailing their
 
 | xref::api/chat/anthropic-chat.adoc[Anthropic Claude]  | text, image ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::no.svg[width=12] ^a| image::no.svg[width=12] ^a| image::no.svg[width=12]
 | xref::api/chat/azure-openai-chat.adoc[Azure OpenAI]  | text, image ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::no.svg[width=12] ^a| image::yes.svg[width=16]
-| xref::api/chat/vertexai-gemini-chat.adoc[Google VertexAI Gemini]  | text, image, audio, video ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::no.svg[width=12] ^a| image::yes.svg[width=16]
+| xref::api/chat/vertexai-gemini-chat.adoc[Google VertexAI Gemini]  | text, pdf, image, audio, video ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::no.svg[width=12] ^a| image::yes.svg[width=16]
 | xref::api/chat/groq-chat.adoc[Groq (OpenAI-proxy)]  | text, image ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::no.svg[width=12] ^a| image::no.svg[width=12] ^a| image::yes.svg[width=16]
 | xref::api/chat/huggingface.adoc[HuggingFace]  | text ^a| image::no.svg[width=12] ^a| image::no.svg[width=12] ^a| image::no.svg[width=12] ^a| image::no.svg[width=12] ^a| image::no.svg[width=12] ^a| image::no.svg[width=12] ^a| image::no.svg[width=12]
 | xref::api/chat/mistralai-chat.adoc[Mistral AI]  | text ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::yes.svg[width=16] ^a| image::no.svg[width=12] ^a| image::yes.svg[width=16]

spring-ai-docs/src/main/antora/modules/ROOT/pages/api/chat/vertexai-gemini-chat.adoc

@@ -124,9 +124,11 @@ Read more about xref:api/chat/functions/vertexai-gemini-chat-functions.adoc[Vert
 
 == Multimodal
 
-Multimodality refers to a model's ability to simultaneously understand and process information from various sources, including text, images, audio, and other data formats. This paradigm represents a significant advancement in AI models.
+Multimodality refers to a model's ability to simultaneously understand and process information from various sources, including `text`, `pdf`, `images`, `audio`, and other data formats. 
+This paradigm represents a significant advancement in AI models.
 
-Google's Gemini AI models support this capability by comprehending and integrating text, code, audio, images, and video. For more details, refer to the blog post https://blog.google/technology/ai/google-gemini-ai/#introducing-gemini[Introducing Gemini].
+Google's Gemini AI models support this capability by comprehending and integrating text, code, audio, images, and video. 
+For more details, refer to the blog post https://blog.google/technology/ai/google-gemini-ai/#introducing-gemini[Introducing Gemini].
 
 Spring AI's `Message` interface supports multimodal AI models by introducing the Media type.
 This type contains data and information about media attachments in messages, using Spring's `org.springframework.util.MimeType` and a `java.lang.Object` for the raw media data.